The objective of this paper is to evaluate the deformation behavior of geogrid reinforced soil barriers of landfill covers using centrifuge model studies. Centrifuge model tests were performed at 40g on soil barriers reinforced with and without scale-down model geogrid subjected to continuous differential settlements using a 4.5 m radius beam centrifuge having a capacity of 2500 g-kN available at IIT Bombay. Differential settlements were induced using a motor-based differential settlement simulator designed for a high gravity environment. Strain gauge based instrumented scale – down model geogrids were used to estimate the actual mobilized tensile load of geogrids at various levels of distortion. Centrifuge model test results reveal that a 1.2 m thick unreinforced soil barrier subjected to an overburden pressure equivalent to that of a cover system experienced cracks extending up to full thickness of the soil barrier and lost its integrity at low distortion levels. A substantial reduction in the magnitude of crack width and depth were noticed when the soil barrier was reinforced with low strength geogrid. In the case of a soil barrier reinforced with a high strength geogrid, the soil barrier was observed to be free from cracking even after subjecting to a distortion level of 0.125. The reason for the significant improvement in the performance of geogrid reinforced soil barrier is attributed to the soil-geogrid interaction and mobilization of tensile load of geogrid layer at the onset of differential settlements. The mobilization of tensile load of geogrid was found to increase with an increase in the geogrid strength, which inturn, helps in restraining soil crack potential even after subjecting to large distortions.
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